Photographic shutter with built-in flash synchronizer



F. A. G. PIRWITZ EI'AL 2,575,121 PHOTOGRAPHIC SHUTTER WITH BUILT-INFLASH SYNCHRONIZER Nov. 13, 1951 2 SHEETS-SHEET 1 Filed NOV. 21, 1947 ByJack .HSzaZrfon NOV. 13, 1951 wn-z r 2,575,121

PHOTOGRAPHIC SHUTTER WITH BUILT-IN FLASH SYNCHRONIZER Flled NOV 21. 19472 SHEETS-SHEET 2 Patented Nov. 13, 1951 PHOTOGRAPHIC SHUTTER WITHBUILT-IN FLASH SYNCHRONIZER Friedrich A. Gustav Pirwitz, Rochester,Gustave Paul Pirwitz, Irondequoit, and Jack H. Sutton, Rochester, N. Y.,assignors to Wollensak Optical Company, Rochester, N. Y., a corporationof New York Application November 21, 1947, Serial No. 787,394

7 Claims. (Cl. 9511.5)

The present invention relates to a photographic shutter with photoflashsynchronizer. An object of the invention is the provision of asimplified, sturdy, and inexpensive form of photofiash synchronizer sodesigned that it may be initially built into a photographic shutter.with a minimum change in the shutter parts as compared with a similarphotographic shutter having no synchronizer.

Another object of the invention is the provision of a photoflashsynchronizer so designed and constructed that the parts may be moreeasily and inexpensively manufactured and more easily and quicklyassembled, as compared with prior synchronizers.

Still another object is the provision of improved and simplified meansfor keeping the photoflash electric circuit always open at all timesexcept when an exposure is being made, so that .when a fresh photoflashbulb is screwed into the socket, there is no danger of prematureflashing thereof.

A further object is the provision of synchronizing means so designed asto be especially adapted to the requirements of relatively low pricedshutters.

These and other desirable objects are accomplished by the constructiondisclosed as an illustrative embodiment of the invention in thefollowing description and in the accompanying drawings forming a parthereof, in which:

Fig. 1 is a diagrammatic front view of a camera shutter according to thepresent invention and the associated photoflash circuit, with the coverplate and other parts of the shutter removed, and with the mechanismshown in set or tensioned position, ready to make an exposure;

Fig. 2 is an enlarged view of a portion of Fig. 1, with parts brokenaway;

Fig. 3 is a view similar to Fig. 1 showing the mechanism in run-downposition at the completion of an exposure;

Fig. 4 is a section taken substantially on the line t--4 of Fig. 3;

Fig. 5 is a section taken substantially on the line 55 of Fig 3; and

Fig. 6 is a plan of a switch lever forming part of the construction.

The same reference numerals throughout the several views indicate thesame parts.

The photofiash synchronizer of the present invention may be applied tophotographic shutters of various kinds or styles. Merely as a convenientillustrative embodiment of the invention, it is here shown as applied toan objective or between-the-lens shutter of the set type (that is, onewhich requires to be set or tensioned by a separate operation before thetrigger is actuated to release the shutter to make an exposure), but itwill be obvious to those skilled in the art that the invention may alsobe used with a shutter of the automatic type (that is, one in which theshutter is first tensioned and then released by a single motion of atrigger member in one direction). For convenience, the particularshutter chosen for illustration of the present invention is a shutter ofknown construction, and may be of substantially the same constructiondisclosed in United States Patent 2,331,568, granted October 12, 1943,for an invention of Pirwitz.

Referring now to the drawings, the shutter comprises the usual annularcasing having the usual outer wall 2| of approximately circular shape,in which casing is a partition plate 22 subdividing the space into ashallow rear compartment containing the iris diaphragm blades and theshutter blades, and a deeper front compartment containing the operatingmechanism. This partition plate conveniently carries an inner tubularwall 23 in which one or more photographic lenses are mounted, the wall23 being associated with an annular beveled ring 2:: which lies just infront of the shutter blades and defines the maximum exposure aperture.This aperture is normally closed, as usual, by a plurality of shutterblades which slightly overlap with each other, and which are opened atthe proper time to make an exposure in known manner. For convenience ofillustration, only one of the shutter blades is here shown, at 25, butthose skilled in the art will readily understand that a series of suchblades is employed. Each blade is pivoted as at 27 to the usual annularblade ring or revolving ring (not shown), and has a second pivot 29extending into an approximately radial slot 31 in a fixed part, so thatwhen the blade ring or revolving ring carrying the pivot 21' is turnedin a clockwise direction around the tube 23, the shutter blades will beopened, and when the blade ring moves in a counterclockwise direction,the blades will be closed.

The shutter blades and the blade ring or revolving ring lie in a rearcompartment of the shutter, beneath the plate 22. As usual, one of theblade pivots 21 extends upwardly through an arcuate slot 3-3 in theplate 22, where it is engaged by the notched or forked end of a leaflever or blade lever 35 pivoted on a stud 3i mounted on the plate 22.When an exposure is to be made, this leaf lever 35 is turned first inone direction and then in the other by a master member or master lever4I pivoted at 43 on a fixed pivot, and constantly urged in acounterclockwise direction on its pivot 43 by a strong motor spring 45mounted on the stud 41 and having an end engaging the stud 49 on themaster lever. A setting lever 5| pivoted at 53 and extending to anaccessible position outside of the casing, has an ear 55 adapted tocontact with the curved surface 51 of the master member 49 when thesetting member 5I is moved downwardly in a clockwise direction from theposition shown in Figs. 1 and 3, thereby moving the master member 4|from the relaxed or rundown position shown in Fig. 3 to the tensioned orset position shown in Fig. 1.

As the master member 4| moves from the relaxed position of Fig. 3 to thetensioned position of Fig. 1, a downturned hook BI on the master memberpasses over the leaf lever 35 and a lug 65 on the master member rides upan inclined or beveled surface 63 on the leaf lever.

and then rides across the top of the leaf lever to maintain the end ofthe master member in somewhat elevated position until the hook GI on themaster member reaches and rides up an inclined or beveled portion 61(thus elevating the end of the master member slightly higher) and thendrops down behind a shoulder 69 on the release lever or trigger 'IIpivoted at I3 and extending out to an accessible position externally ofthe shutter casing. Just as the hook 6| on the master member reaches theshoulder 69, the end of the lug 65 on the master member rides oif of theleaf lever 35, so that the lug 95 drops behind the shoulder I5 on theleaf lever, substantially at the same time that the hook BI drops behindthe shoulder 69 on the release lever. This completes the setting of theparts, and they remain in this position until the trigger or releasemember II is turned in a counterclockwise direction about its pivot I3,which withdraws the shoulder 69 from the hook SI on the master member,allowing the motor spring 45 to turn the master member in acounterclockwise direction about its pivot 43. During suchcounterclockwise motion of the master member, the lug 95 strikes againstthe shoulder I5 of the leaf lever 35, turning this lever in acounterclockwise direction about its pivot 31, thereby moving the pin 21of the blade ring and moving the blade ring itself in a clockwisedirection to open the shutter blades. When the blades are fully opened,the lug 65 slips oil the left end of the leaf lever 35 and the hook ITon the master member II engages the pin 21 and moves it in a reversedirection, thereby closing the shutter blades.

The parts thus far described are all well known in the art, andcorrespond in general to the similar parts disclosed in said UnitedStates Patent 2,331,568. Retarding mechanism for making exposures ofvarious lengths, as well as time exposure and bulb exposure mechanism,usually are employed in conjunction with the parts above described, asindicated in said prior patent. g

It willbe realized by those skilled in the art that the above shuttermechanism is only a convenient example of a typical shutter mechanismwith which the synchronizing mechanism of the present invention may beemployed, and the Th ph fias gs nghr ei xeeel a sre qi the presentinvention constitutes largely a subassembly mounted on the mountingplate 9|, which is supported from the plate 22 by three screws 93, 95,and 91, each surrounded by a spacing sleeve 99. This mounting plate 9|,as best seen in Fig. 4, is supported at an elevation above the plane ofoperation of the master member 4I. Two screws IIlI and I03 screwed intothe plate 9| serve to hold a contact stack or sandwich which, as bestshown in Figs. 2 and 4, comprises first a dielectric plate I at thebottom of the stack, then a metal plate I91, then another dielectricplate I99, and then at the top of the stack another metal plate III.Insulating bushings II3 around the screws IUI and I93 serve to insulatethese screws thoroughly from both of the metal plates I9! and III. Bothmetal plates have their inner edges (toward the center of the shutter)of arcuate form, concentric with a stud II'I screwed into the plate 9I,except that the bottom metal plate III'I has its left corner cut away asindicated at H9 in Fig. 2, and the edge of the cut away portion isinclined or beveled at I2I.

Pivotally mounted on the screw stud H1, and

lying on the top surface of the plate 9!, is a lever I25 having ahook-shaped left end I21 cooperating with a stud I29 fixed in andextending upwardly from the master member 4I This lever I25 has near itsright end an upwardly extending ear I3I against which bears one end of aspring I33 wrapped around the stud III,

and constantly tending to turn the entire lever I25 in acounterclockwise direction about the pivot 1.

At an intermediate point in the length of the lever I25 there arelateral lugs I4I bent up at two opposite sides of the lever. Embracedbetween these two lugs or ears MI and held also by a screw I43 threadedinto the lever I25, there is a lower insulating block I45 andan upperinsulating block I41 and between them (insulated thereby from the screwI43 and from the lever I25) isa metal contactfinger I49. The insulatingblock I45 is held against turning on the screw I49 by means of theearsI4I which tightly embrace the sides of the insulating block, and themetal contact finger M9 is held against turning by downturned ears I5Iturned downfrom the left end of. the member I49 and I53 turned down fromopposite sides of the member I49, tightly embracing the insulating blockI45.

This metal contact finger I49 extends in a generally rightward anddownward direction from the screw I43, when viewed as in Fig. l, and issplit throughout part of its length, as indicated, into two fingers I55and I51, the former being ofiset downwardly so as to rub on the topsurface of the contact plate II]? as indicated in Fig. 4, and the fingerI5I being offset to rub on the bottom surface of the upper contact plateI I I. This member I49 with its fingers I55 and I5! is made of metalwhich is resilient as well as forming a good electrical conductor; forexample, beryllium copper. The parts are initially formed with enoughoffset between the fingers I55 and I51 so that these fingers make a goodwiping contact pressing firmly against the members I9 and III,respectively.

When the master member 4| is in its set or tensioned position shown inFig. 1, the stud I29 on the master member, engaging the hooked end I2'Iof the lever I25, holds this lever against the forceof the spring I33 tomaintain the contact fingers I55and I5I to the position shown in Figs.

5. 1 and 2, wherein the finger I51 is in contactrwithv andpressesupwardly against the under surface of the contact plate- Iii, but theother contact finger I55 liesopposite the notch I I9 in the lowercontact plate IE'I and consequently is spaced from the plate I07 anddoes not make electrical contact therewith. When the shutter is trippedor released, the consequent counterclockwise movement. of the mastermember II about its pivot 43 carries the stud IEii-downwardly from theposition shown in Fig. .1 to the position shown in Fig. 3, whichmovementallows the lever I25 to turn counterclockwise underztheinfluence of its spring I33, following alongwith the movement of.thestud i253. Thiscounterclockwise movement of the lever. I25carrieswith it the contact fingers i5?) and; I51, the finger I57 sliding orwiping along the under surface of the contact plateIII, while the fingerI55, initially spaced from the contact-plate E91, makes contact withthis plat iii? after. a very slight initial movement,..rides up theinclined r beveled shoulder 52! on the plate IEi'l, and-thereafterslides or wipes along the upper surface of the plate till. In this way,almost at the beginning of the movement of .the master member ii thefingers I55 and i? establish an electrical connection between'the twoplates till-and. I I I. This contact continues. for an appreciable.time,v while the fingers 555 and i5? wipe over the contact plates, thusassuring ample time of contact to set off whatever flashlight bulb orother photcflash device is electrically connected to the plates I6! andIII.

The external photoflash circuit and other parts may be of anyconventionalkind, including, for example, a photofiashbulbdiagrammatically indicated at it! inFig. I, screwed into the con-=ventional socket and connected to a battery or othersource'ofelectricity i83.- The circuit wires indicated diagrammatically at Hi5and it? lead, respectively, to an outersleeve I69 and an inner conductor5'?! mounted on the shutter casing but insulated from each other andfrom the shutter casing in the conventional.mannerwell known in the art.The sleeve Ifidand conductor IlI are made to fit the standardconventional connection plug used with flashlight circuits.

She inner end of the conductor i? t, after pass ing through the wall of.the shutter casing, is connected as by solder iIfi'to a wire I75 whichhas its other end suitably connected, as by solder I'I'i, to the lowercontact plate It'll. The other side of the photofiash circuit. (that is,thesleeve IE9) is connectedjto the upper contact plate HI throughmechanism which opens or breaks the circuit just as the master member 4Ireaches its completely released or run-downposition, so as to avoidaccidental and unintentional discharge of a new photofiash bulb whichthe photographer may insert in the socket while the shutter is still inits released or run-down position, before it is reset or tensioned forthe next exposure. Such means for opening or breaking the circuit underthese circumstances, although broadly old, is new in the improved formhere shown. It comprises a resilient conductor strip i8! mounted on andsupported by the inner end of the conducting sleeve I59, inside theshutter casing, this strip i3! extending leftwardly from its support tothe vicinity of a downturned ear E83 (Figs; 1 and a) on the uppercontact plate Ill. The strip ISI is formed of resilient material whichis a good electrical conductor (for example, beryllium copper) and ismade with initial tension whichzconstantly diallyinwardly. toward the.centerof the shutter,

to bring it into firm contact with the ear I83. It.

may, however, be displacedradially outwardly away from the ear I33 bymovement of a switch member I9I pivotally mounted on the screw stud I93.screwed into the supporting plate 9|, and carrying an upstanding arm Isurrounded by a IELYGI'OIISIGEVB of insulating material EQIwhich isadapted, under certain conditions, to press against the inner face ofthe spring conductor strip i33and move it against its spring tension,radially outwardly away from the ear I 33, from the ,positionshown inFig. l to the position shown inLFig'. 3.

This switch lever IQI .is operated by a stud 23I fixed to1the master.member II and coming up through an appropriate slot in the plate 9!. Asthe master member 4: reaches the end of its counterclockwise movementduring the making of an exposure, the stud ZQI hits against the edge oftheswitchlever I95 and moves this switch lever from the position shownin Fig. 1 to the position shown in Fig. 3, so that the insulatingsleeveIt! on the ear I95 strikes against the conductor strip WI and thruststhis member radially outwardly from the position shown in Fig. 1 to theposition shown in Fig. 8, moving it away from the ear E83 and breakingthe circuit at this point. Then when the shutter is tensioned ready forthe next exposure, the tensioning movement or clockwise movement of themaster member 5 moves the stud back from the position of'Fig. 3 to theposition of Fig. l, and during the latter part of such movement the studhits against the hook 2&3 on th switch lever I9! and swings the switchlever in a clockwise direc tion about its pivot MS, from the positionshown inFig. 3 back to the position shown in Fig. 1, thus allowing theresilience of the conductor strip RBI to move it back into positionagainst the ear I83, completingthe circuit at this point. However, thismovement of the switch lever I95 and closing of the circuit between IBIand I 83 does not. occur until after the stud I29 on the master memberhas moved the lever I25 far enough to swing the contact'finger I 55 pastthe beveled edge [2i andinto the notch I9 of the lower contact plateIli'l, opening the circuit at this point. Thus, whenthe shutter isbeing'set or tensioned, the circuit at ifil-l83 does. not close untilthe circuit hasbeen opened at the point 557?, 555, so that there is nodanger of accidentally flashing a photofiash bulb during the resettingoperation, even if a fresh bulbihas been inserted in the socket.

Tohold the switch lever i9i in one position orthe other andto insurethat it will not become accidentally displaced from either position,frictional means are provided- As best seen in Fig. 4, the pivot studI93'on which the switch lever iii is mounted, is surrounded by a coiledspring Zii which presses firmly down on the top of the switch lever I9i,thus pressing it against the top surface-of the mounting plate 9i. Thisproduces a considerable degree of friction between the switch'leverandthe stationary mounting plate, to prevent accidental displacement. Inorder to hold the switch lever with even greater certainty, in itsswitch-opening position, the switch lever is provided on its top with apunched depression 253' (Figs. 4 and6)- thus forcing a thin V-shaped ribMS of metalto protrude from the bottom'surface of the switch lever,which rib 2I5 retaining means and detent is arranged approximatelyradially with respect to the pivot stud I93. The top surface of thestationary mounting plate 9I is provided with a groove 2I'I (Fig. 1) ina location underlying the position occupied by the rib 2I5 when theswitch lever is in the switch-opening position of Fig. 3. Thus when themaster member is in its rundown or relaxed position and the switch leveris in the switch-open position of Fig. 3, the rib 2E5 on the bottom ofthe switch lever will be seated in the groove 2 of the plate 9i. Thespring 2 not only holds the switch lever frictionally engaged with theplate 9|, but specifically holds the rib 255 down in the groove 2 I1. Ittakes substantial force (considerably more than the resilient force ofthe conductor strip I8I) to displace the switch lever I9I in a clockwisedirection from this position, to cause the rib 2I5 to ride up out of thegroove 2, and there is no appreciable likelihood or possibility of theswitch lever accidentally moving from the switch-open position to theswitch-closing position until it is positively moved by contact of themaster member stud ZEEI with the switch lever hook 253 just at the endof the setting movement of the master member.

The function and operation of each part of the shutter have beendescribed above in connection with the description of the constructionof that part. To recapitulate briefly the operation of the shutter as awhole, it is seen that, starting with the shutter in its run-down orrelaxed position shown in Fig. 3, the shutter is first tensioned bymoving the setting member Si in a clockwise direction, whereupon the lug55 will engage the curved part 51 of the master member and swing themaster member against the tension of the strong motor spring 45 in aclockwise direction about its pivot 43, from the position shown in Fig.3 to the position of Fig. 1. The hook SI on the master member, towardthe latter end of the tensioning movement, rides over and falls behindthe shoulder 69 on the release lever or trigger 7II. During this settingmovement of the master member, the stud I29 thereon displaces the leverI25 in a clockwise direction about its pivot II'I, against the tensionof its spring I33, and thus carries the contact members leftwardly alongthe contact plates I01 and III until the lower contact member I reachesthe notch IE9 and moves out of contact with the plate I07. Just afterthe contact I55 moves away from the plate Ill? to open the electriccircuit at this point, the stud 2! on the master member hits the hook203 on the switch lever I9I, and overcomes the frictional resistancecaused by the spring pressure of the switch lever on the plate SH and bythe engagement of the ridge 2I5 on the switch lever in the groove 2I'Iof the plate SI, and swings the switch lever from the position shown inFig. 3 to the position shown in Fig. 1, thereby allowing the springcontact I8! to move against and make electric contact with the ear I83on the contact plate III. The parts are now ready for making anexposure, and, if a fresh flashlight bulb ISI has been screwed into theusual socket, the only open part of the entire electric circuit is thebreak at the notch H9 between the contact finger I55 and the lowercontact plate I57. All other parts of the circuit are closed.

The exposure is now made by depressing the release member or trigger'II, turning it in a counterclockwise direction about its pivot I3.

This withdraws the shoulder 69 from the hook III on the master member4|, allowing the stiff motor spring 45 to turn the master member in acounterclockwise direction about its pivot 43, as rapidly as ispermitted by the time delay mechanism which is usually incorporated inshutters of this type, but not here shown. During this counterclockwisemovement of the master member, the stud I29, almost at the beginning ofthe movement, moves downwardly far enough so that the lever I25 can turn(under the influence of its own spring I33) counterclockwise about itspivot II'I, far enough to bring the contact finger I55 into engagementwith the lower contact plate I61. The upper contact finger I5! isalready in engagement with the upper contact plate III. The lowercontact finger I55 then wipes along the surface of the plate I81, whilethe upper contact finger I5! is wiping along the surface of the contactplate III, the fingers I55 and I51 thus establishing an electric contactbetween the two plates IIII and III, which contact continues long enoughto make sure that the photoflash bulb IGI is ignited.

While the counterclockwise movement of the master member 4| is allowingthe lever I25 to swing as above described, such counterclockwisemovement is also causing the lug 65 on the master member to hit againstthe shoulder I5 on the leaf lever 35, turning this leaf lever in acounterclockwise direction about its pivot 31 and, through the action ofthe pin 27, causing the shutter blades to open. Then the hook TI on themaster member, during continued movement, hits against the pin 21 andmoves it in the opposite direction, causing the shutter blades to close.Toward the latter part of this movement of the master member, the studZIII thereon hits against the switch lever I9! and moves itcounterclockwise on its pivot I93, to the position shown in Fig. 3,which causes the ridge 2I5 to seat in the groove 2II and at the sametime causes the insulating covering I9'I on the ear I to strike againstthe spring conductor member ISI and move this conductor member slightlyradially outwardly, away from the ear I33 of the top contact plate III,opening the circuit at this point. This occurs, as above stated,practically at the end of the movement of the master member, and at thevery end of such movement, an upstanding ear 23! on the master memberstrikes against a cushioning pad 233 on the side of the shutter casing,which pad serves to cushion the blow or jar caused by the suddenstoppage of movement of the master member. The parts come to rest in theposition shown in Fig. 3.

The exposure is now complete and the shutter may be reset for the nextexposure, and a fresh flash bulb I 6 I may be inserted in the socket,either before or after resetting the shutter, without danger ofpremature flashing of the bulb in either event. If the fresh bulb isinserted in the socket before the shutter is retensioned, the electriccircuit is opened between the members I8! and. I83, and during theresetting operation the circuit is opened between the members I01 andI55, just before the circuit is closed between the members IQI and S83.

This synchronizing mechanism being intended for a relatively inexpensiveshutter, there is no provision, in the preferred form here shown, foradjustment of the timing relation between the closing of the flash bulbcircuit and the opening of the shutter blades, in order to accommodatethe shutter especially to flash bulbs having different awn-121 periodsof lag in the production. of maximum brilliance of light after theelectric circuit is closed. It is known that various kinds of flashbulbs have different lag time.' 'It is well understood by thoseskilled'in theart that two of the most popular kinds of photofiash bulbshave lags of milliseconds and 20 milliseconds, respectively, meaningthat the most intense part of the flash or" light is produced atfive'one thousandths of a second or twenty one-thousandths of a second,respectively, after the electric'circuit is Lclosed.

In the present shutter, the sizes andproportions of the parts are sodesigned that,.in'the of'an exposure, the contact leaf i555 will makecon tact with the plate liil' atz'approximately emanseconds before*theishutter blades reachftheir maximum open position." Hence :theshutter may "be used'at all'exposure speeds with-flashbulbs' of thetypehaving a lag-of 5zmilliseconds,-andin addition, itmay be usedatexposure speeds of secondor slower withfiash bulbs of the type having alag of 20 milliseconds, for at such speeds the blades remain open longenough to takeadvantage of a hash which reaches its peakintensity aboutmilliseconds after the shutter blades first reach their maximum openposition.

I Although the contact fingeri5! has-been shown as being constantly'incontact with theplate I i i,

it will be obvious thatthis plate also could be notched at its left end,if' desired, so that the contact fingers I55 and i 51 would -be clearotboth plates)? and! H in .theopen position; if desired. It is. seenfrom the. foregoing" disclosure that, the

above-mentioned obj ects of the inventionare; ad- -mirably,fulfilled.-It is, to'be understood thatthe foregoing disclosure is given by i-wayof illustrative .example only, ratherthanby way of'limitation, :and thatwithoutdepartingfrom the invention,

the details may be varied within the scope :of the appended claims.

. What is claimed is:

1.. In a-photographic shutter of the type including amastermembermovablein a tensioning direction to condition. the shutter.for making an exposure and movablein the opposite direction to .make anexposure, a. spring .tensioned by-movement of -.said master :member-inssaid tensioning direction and furnishing. the power to; move saidimasternmember inv said opposite direction, and electric circuit partsforoperating a flash lampin synchronismwith the. exposure; thecombination of a..first switchand asecondswitch electrically connectedinsaid circuit .in. series with'each other, a first switch.operatingmember movable between switch-open and switch-closedpositions, a spring erating member against the'tension-of its spring toswitch-open position during the latter part of movement of said mastermember'in said tensioning directionandto move. saidsecond switchoperating member to switch-closed position substantially'at thecompletion; of movement. of said master member .in said. tensioningdirection.

2. In aiphotographic shutter of the type including a master membermovable in a tensioning direction to condition the shutterfor makingsanex- ;posure :and .movablein. the opposite direction to "eluding a=mastermember movable .move said master 'iember in said opposite tion, andelectric ci "for swinging .movement and make an exposure, a springtensioned'by movement of saidmaster member in said tensioning directionand furnishing the power to move said master member in said oppositedirection; and electric circuitparts for operating a flash lamp insynchronism with the exposure; the combination of a first switch and asecond switch electrically connected in said circuit in series with eachother, a first switch operating membermovable between switch open andswitch-closed positions, a spring constantly tending to move saidoperating member from switch-open position toward switchclosed position,a second switch operating member movable between switch-open positionand switch-closed position, means tending to hold said second switchoperating member in either of its positions in which it is set, anabutment part on said master member for engaging said first switchoperating member to move it against the force of its spring'fromswitch-closed to switch-open position when said master member moves in atensioningdirection, said spring of said first switch operating memberkeeping said operating member in engagement with said abutment part andserving to move'said operating member to switchclosed position as fastas permitted by movement of said master member in-an exposure-makingdirection, and'an abutment parton said master member forengaging saidsecond switch opertion and tomove it to switch-open positionsubstantially-attire completion of movement ofqsaid mastermember inanexposure-making position.

3..Arphotographic shutter of the type including ashutter blade movablefrom a closed position'to an open position and back to a closedposition, a master member movable toopen and 40' electric circuitconnectionsfor operating a flash lamp-in synchronism with said exposure,charthen to close said blade to make an exposure, and

lever for'contr'olling the time and rate of movement of said switchlever toward closed position in accordance with the time and rate ofmovement of said master member, said shutter being furthercharacterizedby'the provision of a second switch lever, and meansoperated by said mast r member for moving said second switch lever toswitch opening position after the first switch lever has moved to switchclosing position and for'moving said second switch lever to switchclosing position after the first switch lever has moved to switchopening position.

4-. In a photographic shutter of the type inin a tensioning direction tocondition the shutter for making nsioned by sioning direction and t. thepower to r it par flashlamp in synchrthe combination of a control inmber mounted a portion lying in the path of travel of said mastermemmovement of saidmasterimemberin a tensioning direction, a springseparate from said control member and acting on said control member andtending to move it in the opposite direction to keep it constantly inengagement with said master member so that said control member will movein the opposite direction as fast as permitted by movement of saidmaster member in the opposite direction, and a switch in said circuitincludinga conducting member mounted on and carried by said controlmember and a second conducting member mounted in position to be spacedfrom the first conducting member when said control member is at thelimit of its travel in the first direction and to be engaged by saidfirst conducting member in wiping contact therewith as said controlmember moves in the opposite direction, said combination furtherincluding a second switch electrically connected in series with saidfirst switch, and means operated by aid master member for closing saidsecond switch substantiall at the completion of movement of said mastermember in said tensioning direction and for opening said second switchsubstantially at the completion of movement of said master member insaid opposite direction.

5. In a photographic shutter of the type including a master membermovable in a tensioning direction to condition the shutter for making anexposure and movable in the opposite direction to make an exposure, aspring tensioned by movement of said master member in said tensioningdirection and furnishing the power to move said master member in saidopposite direction, and electric circuit parts for operating a flashlamp in synchronism with the exposure; the combination of a controlmember mounted for swinging movement and having a portion lying in thepath of travel of said master member to be engaged and swung in onedirection by movement of said master member in a tensioning direction, aspring separate from said contact member and acting on said controlmember and tending to move it in the opposite direction to keep itconstantly in engagement with said master member so that said controlmember will move in the opposite direction as fast as permitted bymovement of said master member in the opposite direction, and a switchin said circuit including a conducting member mounted on and carried bysaid control member and a second conducting member mounted in positionto be spaced from the first conducting member when said control memberis at the limit of its travel in the first direction and to be engagedby said first conducting member in wiping contact therewith as saidcontrol member moves in the opposite direction, said combination furtherincluding a second switch electrically connected in series with saidfirst switch, a switch operating arm movable to one position to closesaid second switch and movable to another position to open said secondswitch, frictional means holding said arm in either of its two positionsuntil displaced therefrom by superior force, and a portion on saidmaster member for engaging said switch operating arm to move it toswitch closing position substantially at the completion of movement ofsaid master member in said tensioning direction and to move said arm toswitch opening position substantially at the completion of movement ofsaid master member in said opposite direction.

6. A photographic shutter of the type including a shutter'blade movablefrom a closed position to an open position and back to a closedposition, a master member movable to open and then to close said bladeto make an exposure, and electric circuit connections for operating aflash lamp in synchronism with said exposure, characterized by the factthat said electric circuit connections include a stationary switchassembly having a pair of spaced conducting plates arrangedapproximately in parallel planes spaced from each other with one platein at least partly overlying relation to the other plate, and a movableswitch member shiftable in timed relation to the movement of said mastermember and having conducting parts engageable, during part of itsmovement, with both of said spaced conducting plates to complete theelectric circuit between the plates, said movable switch member beingmounted for swinging movement about an oscillatory axis approximatelyperpendicular to said planes of said plates and having conducting meansentering the space between said plates and arranged to rub on the uppersurface of the lower conducting plate and on the lower surface of theupper conducting plate during an effective shifting movement of saidswitch member, with the conducting means of said switch memberconstantly engaged with a surface of one of said conducting plates inall normal positions of said switch member and with said conductingmeans out of engagement with the other of said conducting plates whensaid switch member is in one position and in contact with said other ofsaid conducting plates when said switch member is-in other positions,said shutter being further characterized by a spring tending to movesaid switch member to switch-closing position, and an interconnectionbetween said switch member and said master member efiective to hold saidswitch member in switch-open position when said master member is in aset position at one end of its path of travel and to release said switchmember for movement toward switch-closing position only when and at therate that said master member moves from its set position toward theother end of its path of travel.

7. A structure as defined in claim 6, in which said conducting means ofsaid movable switch member includes a metal strip split longitudinall.vthrou h part of its length and having part of the metal on one side ofthe split offset in one direction to engage with one of said conductingplates and part of the metal on the other side of the s lit ofiset inthe opposite direction to engage with the other of said conductingplates.

FRIEDRICH A. GUSTAV PIRWITZ. GUSTAVE PAUL PIRWITZ. JACK H. SUTTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,968,597 Blake July 31, 19342,049,735 Grogin Aug. 4, 1936 2,145,917 Boesser Feb. 7, 1939 2,282,850Brownscombe May 12, 1942 2,358,941 Schwarz Sept. 26, 1944 2,404,526Pirwitz July 23, 1946 2,405,741 Fuerst Aug. 13, 1945 2,474,378 Simmon etal June 28, 1949 2,502,668 Pirwitz Apr. 4, 1950

